Process for increasing the drum drying rate of polychloroprene by adding polyvinyl methyl ether



United States Patent ()fi" 3,365,518 Patented Jan. 23, 1968 3 365 51s PROCESS FOR iNcREAsiNG THE DRUM DRY- ING RATE OF POLYCHLOROPRENE BY ADD- ING POLYVINYL METHYL ETHER 140 p.s.i.g., and, before drum-drying, when the solids content of the latices are about 44%, varying amounts of Lutonal M-40 polyvinyl methyl ether having a viscosity of 43,000 centipoises in 50% aqueous solution,

5 an inherent viscosity of 0.35, molecular weight 40,000, 'ggg flfi g g ifiifaflf$gl$ffii are added to separate samples, the amount being calcu- Wilmingtond.acorporafionofnelaware lated as the we ght of polyvinyl methyl ether on the No Drawing. Filed Aug. 2, 1965, Ser.No. 476,750 weleht 0f the n p y e drymg 1s earned out 3 Cl i ((31, 260-390) under such conditions as to yield a dried polychloroprene 10 containing approximately 1% volatile material. The dry- This invention concerns improvements in and relating ing rates of samples containing Lutonal M-40 are comto the manufacture of neoprene, i.e., polychloroprene pared with the drying rates of control samples containing (poly-Z-chlorobutadieue-1,3), More particularly this in no Lutonal M-40 in the following table.

TABLE Drum speed, r.p.m. Rate of Latex Feed, Drying Rate,

lbs/hr. lbsJhr. Drying Lutonal Rate M40, percent Increase, Control Lutonal Control LutonaP' Control Lutonal Increase percent M-40 M-40 M-40 vention relates to the isolation of neoprene from its poly-m- Example H erization mixture.

f to the Present mventfom polychlorgprgtne A polychloroprene latex is prepared according to the dlslp g i g by ff fi l 2 2:; procedure of Example I of British Patent 807,496. The p0 ymlenzailon e Ore 6 p0 o Opren. 1S 1s latex is dried on a laboratory drum-dryer at 15 rpm. from its dispersion by drum-drying, a polyvinyl methyl at a Steam res u e of 145 f 1 ether is added to the dispersion in amounts of about 0.03 p s r i W1 quan 1 ms 0 p0 to 20% by Weight of the pblychlomprena vinyl methyl ether Lutonal M-40) added to the latex The manufacture of polychloroprene may otherwise 40 before drying as shown in the following table. The feedbe carried out by conventional means, for example as del of h latex to the drum'dryer 1S a'dlllsted so to scribed in British patent specification No. 807,496 (US. tall} 3 dned Polychloroprene Containing 1% Volatlle 2,914,497), involving forming an emulsion of chloroterial. prene, polymerizing, short-stopping the polymerization, stripping out unpolymerized monomer and after adding TABLE the polyvinyl methyl ether according to the invention, drum-drying the dispersion to form a film of polychloro- Lutonar, Latex Feed, Drying Rate, Drying Rate prene, which may then be processed, e.g., commlnuted, MAO, percent lbs /h lbsjhr, I icma e,per ent according to conventional techniques.

The polyvinyl methyl ether may be, for example, the None-contr0l 77.3 29.4 polyvinyl methyl ether sold by Badische Anilin- -und Soda 22 33:3 8:; Fabrik as Lutonal M4O (in the United States as Gan- 88.4 33.6 14.3 trez M-l54 by General Aniline and Film Corporation). It has been found convenient to add the polyvinyl methyl 55 ether in the form of an aqueous solution, e.-g., containing about 15% to 20% by weight polyvinyl methyl ether, at a time when the p olhychloi;1oprene dispersion contains about other polychloroprene latices may be substituted for 40 to Welg tsoh. those above and similar improvements in drying rates The addition of polyvinyl methyl ether has been found 0 obtained to be of advantage since the drying times on a drum- 6 h dryer (usually heated by Steam at 25 to 150 PSi.) have T e increase in drying rate obtained by using more than been significantly reduced in comparison with prior art about 2% PQIYVHIYI methyl etherflbased on the Poly drunkdrying processes on polychloroprene latices com chloroprene, is usually not appreciable. The preferred tainiiig no polyvinyl methyl ether. The addition of polyof Polyvmyl methyl ether 15 about to 19% vinyl methyl ether effects no significant change in the by Welghf of F y p p processing and curing of the resulting polymer. W at Is cl i ed is! The invention will be further described in the following 1. A process for increasing the drying rate of an aqueexamples. All parts and percentages are by weight unless ous dispersion of polychloroprene which comprises niixotherwise indicated. ing with said dispersion about 0.03 to 2.0% of poly- Example 1 vinyl methyl ether by weight of polychloroprene and drum- Polychloroprene latices are prepared and dried as dedrying Said mixed dispersion; scribed in Example 5 of British Patent specification No. A l' as defined 111 Clam! 1 Where sald P Y' 807,496 except that a larger drum-dryer of S-feet .diamvinyl methyl ether is present in amounts of about 0.03 eter is used at the speeds shown, the steam pressure is to 1.0% by weight of said polychloroprene.

3. A process 'for increasing the drum-drying rate of a polychloroprene aqueous dispersion having no more than 45% by weight solids which comprises mixing with said polychloroprene dispersion about 0.03 to 1.0% of polyvinyl methyl ether by Weight of said polychloroprene and drum-drying said mixed dispersion so that the dry polychloroprene contains no more than about 1% by weight of volatile material.

References Cited UNITED STATES PATENTS 3,049,501 8/1962 Howland et a1. 260-174 5 MURRAY TILLMAN, Primary Examiner.

M. .T. TULLY, Assistant Examiner. 

1. A PROCESS FOR INCREASING THE DRYING RATE OF AN AQUEOUS DISPERSION OF POLYCHLOROPRENE WHICH COMPRISES MIXING WITH SAID DISPERSION ABOUT 0.03 TO 2.0% OF POLYVINYL METHYL ETHER BY WEIGHT OF POLYCHLOROPRENE AND DRUMDRYING SAID MIXED DISPERSION. 